The present invention relates to check valve assemblies, and in particular to check valves in which an O-ring is used as the sealing element.
Check valves have been used in the past in which an O-ring is the sealing element, as typified by the patents to Davis, U.S. Pat. No. 3,335,751 and the patent to Bogossian, U.S. Pat. No. 3,590,851.
In devices of the Davis type, the O-ring is embedded in one surface and engages a second seating surface perpendicular to the centerline of the conduit to close the valve. It has been found that valves of this type often do not provide a sufficiently tight closure to prevent leakage. Valves of the Bogossian type utilize a valve seat which is inclined with respect to the centerline of the valve, and the contact of the O-ring with the inclined seating surface is more secure. However, valves of this type have been found to often stick in the closed position because the O-ring becomes wedged between the poppet element and the seating surface, particularly when only low pressure is available to open the valve.
In valves of the Davis and Bogossian types, both ends of the poppet element must be larger than the intervening seat to accommodate the O-ring on one side and a spring retention member on the other. This type of construction is difficult to achieve because of the problems involved in assembling the poppet assembly from two or more parts while it is located in the valve.